JP3495915B2 - Cold forming equipment for metal rings - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cold-rolling and forming metal ring-shaped parts such as inner and outer rings of ball bearings, or various sleeves, and particularly excellent in forming dimensional accuracy and less troubles. The present invention relates to a metal ring cold forming apparatus having excellent productivity.

[0002]

2. Description of the Related Art As a means for manufacturing a ring-shaped component made of metal, particularly steel, represented by inner and outer rings of a ball bearing, FIG.
As shown in FIG. 1, a ring-shaped material ring obtained by cutting a material tube into a ring is formed on the outside of the material ring 2 for forming a roll 10 for forming an outer surface and for passing through the material ring 2 for forming an inner surface. An apparatus for sandwiching between the mandrels 20 and performing cold rolling and expansion molding is used. The mandrel 20 is generally supported by a mandrel receiving roll 30. Various improvements have been made to this type of device in order to improve the dimensional accuracy of products or improve the productivity. For example, in Japanese Examined Patent Publication No. 4-743, slippage between the mandrel receiving roll 30 for preventing the bending of the mandrel and the mandrel 20 is prevented, and the roundness is defective due to the deviation of the inner and outer surfaces of the product due to the slip. An NC control means for prevention is described, and it has been proposed to use a servomotor as its drive source.

Generally, in a commercially available apparatus, the gap between the forming roll and the mandrel is set according to the rolling amount of the ring supporting roll or the ring during forming during rolling in order to prevent runout of the ring during forming during rolling. Various moving means for adjusting are adopted. For example, the mandrel receiving roll was fed with jack screws. Or it was due to pressure fluctuations in the hydraulic cylinder. However, conventional devices have not always been satisfactory to meet the recent demanding demands of users on dimensional accuracy and cost of products.

[0004]

The problem to be solved by the present invention is that the roundness of the outer ring and the inner ring of the ball bearing was 0.5 to 1.0 mm in the prior art. It is an object of the present invention to provide a cold forming apparatus for a metal ring, which can stably produce a product having an outer diameter of 1 mm or less, for example, an outer diameter of 120 mm, with a deviation of the outer diameter of ± 0.2 mm with high productivity.

[0005]

The means of the present invention for solving the above-mentioned problems is, in the invention of claim 1, a forming roll.
10, mandrel 20 and mandrel receiving roll 30
And arrange them horizontally and on the same straight line,
(A) Forming roll 10, mandrel 20, mandrel receiver
Crawler roll 30, movement guide device 40 for mandrel 20,
And movement guide device 50 for mandrel receiving roll 30
Are the upper wall surface body 71, the lower wall surface body 72, and the front wall surface body.
73 and a rear wall body 74
(B) the forming roll 10 is attached to the roll shaft 1
1 is made horizontal by the upper wall surface body 71 and the lower wall surface body 72
It is attached to the front wall body 73 of the restraint in a restrained state, and
Ndore Le 20, mounted et the arrested state to the lower wall surface 72
(D) The mandrel receiving roll 30 has an upper wall surface body 71.
And linear motion guide mounted between the lower wall body 72 in a restrained state
It is attached to the block 46 with the roll shaft 31 horizontal.
(E) The linear guide block 46 is an AC servomotor.
91 drive screw mechanism 80 from rear wall surface 74
The position must be controlled and attached to the rear wall surface 74 in a restrained state.
In the cold forming device for a metal ring, the forming roll 10
Links 121, 1 having the roll shaft 11 of the rotation axis as the rotation axis
22 is attached rotatably, and two links 121, 12
Two backup rolls 131, 132 for backing up the ring 3 during molding are attached to the rear end of 2, and two links 121, 132 are provided so that the two backup rolls 131, 132 are located above and below the ring 3 during molding. 122 are crossed, and the front ends of both links are opened and closed by expansion and contraction of the pneumatic or hydraulic pressure cylinder 150 via the coupling link 141, so that two backup rolls 131, 13 are provided.
A cold-forming apparatus for a metal ring, characterized in that the ring 3 can be backed up during molding in 2.

According to the second aspect of the present invention, the linear gauge device 110 driven by the air cylinder 111 is attached to the linear motion guide 47 on the upper wall body 71 , and the arm 113 extends downward from the linear gauge device 110. Then, the two free-rotating touch rolls 114 and 115 are vertically separated from each other in the vicinity of the tip of the arm 113, and both touch rolls 114 and 115 are attached.
115 is positioned in two contact points on the rear surface of the ring 3 during molding with a small average pressure in a constant contact state, the outer diameter of the ring 3 during molding is constantly monitored, and it is linked to the position control of the mandrel receiving roll 30. The cold forming apparatus for a metal ring according to claim 1.

According to the invention of claim 3, in claim 1 or 2
The described metal ring cold forming device is further equipped with a material ring.
The mandrel 20 is attached from the axial side to the forming position of the material ring 2.
A cold-rolling apparatus for a metal ring, comprising a mandrel feed mechanism 90 driven by an AC servomotor 92 provided on the axial side of a material ring for feeding to a workpiece.

In the invention of claim 4, the upper wall surface body 71 is
A linear motion guide device 170 is erected on the upper surface of the arm 171. The linear motion guide device 170 descends downward from a hole 75 opening in the upper wall body 71 and has an chucking unit 172 at the lower end for gripping a material ring. In addition, the timing of the mandrel feed mechanism 90 is controlled to synchronize the supply of the material ring 2 and the retreat timing of the mandrel 20 to prevent the mandrel 20 and the material ring 2 from interfering with each other.
The cold-rolling apparatus for a metal ring according to any one of claims 1 to 3, further comprising an AC servomotor 93 for vertically moving 71.

As described above, the cold-forming apparatus for a metal ring according to the present invention, by adopting the above-mentioned means, can stably obtain the dimensional accuracy of the roundness of 0.1 or less in the manufacture of the inner and outer rings of the bearing. In addition, the number of failures is extremely small, the generation of defective products due to the failures is eliminated, and the productivity is greatly improved.

That is, as a mounting frame for the forming roll, the mandrel and the mandrel receiving roll, which are the basic constituent elements of the cold forming apparatus, conventionally, a frame having no ceiling surface portion or a frame having a ceiling portion made of beams is used. However, these are thought to cause distortion in the frame due to long-term use,
It has been difficult to stably meet the recent customer requirements for product dimensional accuracy. In the present invention, since the frame body is a constraining frame body having a wall surface structure and the ceiling portion is also surface-supported, the constraining frame body is provided even for long-term use by additionally including other constituent requirements of the present invention. It is now possible to maintain stable and strict dimensional accuracy without distortion. Also,
In the present invention, the linear movement guide and the AC servomotor control are all adopted as the mandrel receiving roll and the mandrel feeding mechanism, thereby completely solving the above-mentioned conventional problems.

The feature of the first invention of the present invention is that
In addition to the features of , prevent runout during molding of the material ring,
A backup roll for always supporting the correct molding position is provided, and these backup rolls are uniformly pressed from two points above and below the molding position of the material ring by an air cylinder or a hydraulic cylinder. Therefore, the ring is prevented from swinging due to rotation during molding. According to the present invention, the backup force by the operation of the air cylinder or the hydraulic cylinder can be easily changed according to the processing purpose due to the characteristics of the material of the material ring, the size of the material ring, the degree of processing, etc. As a result, the roundness of the molding ring is improved, and an accurate backup can be added according to the material of the material ring, and the quality can be improved.

According to a second aspect of the present invention, a free-rotating touch roll is constantly pressed against the outer peripheral position of the material ring above and below the molding processing position of the material ring, and the contact position is detected by a linear gauge to detect the outside of the ring under molding. The diameter is monitored and fed back to the moving mechanism of the mandrel receiving roll to be linked with the position control of the mandrel receiving roll.

Further, according to the third and fourth aspects of the invention, by using the AC servo motor control in the axial feed mechanism of the mandrel and the feeding device of the material ring to the molding processing position, the material ring molding processing is performed. It is possible to reliably prevent the interference between the mandrel and the material ring by synchronizing the timing of the supply to the position and the retreat of the mandrel. Further, when the size is changed, the centering of the forming roll and the mandrel can be quantified, and the track misalignment can be kept within 0.1 mm, so that high dimensional accuracy can be maintained and troubles can be effectively reduced.

Further, in the past, the mandrel axial feed mechanism was operated by hydraulic pressure, so a receiver was required to prevent it from moving too far, and the intermediate positioning was not sufficient. On the other hand, in the fourth aspect of the present invention, positioning can be accurately performed by the AC servomotor, and no receiving is required.

In addition to the above-mentioned synchronization of the feed of the material ring and the retreat of the mandrel, a fourth aspect of the present invention is to install the material ring vertically on the upper wall body by vertically setting a linear motion guide device. Since it is supplied to the molding processing position from above through the opening provided in the wall body, the material ring can be stably provided by the linear guide without interfering with other members such as the mandrel and the mandrel receiving roll. It is effective because of maintaining the above high dimensional accuracy and reducing troubles.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is shown in FIGS.
Will be described with reference to. FIG. 1 is an elevational view showing a metal ring cold forming apparatus according to the present invention with a part thereof omitted.
The right side of the figure is the front side and the left side is the rear side. Figure 2
FIG. 3 is a plan view schematically showing the cold forming apparatus for a metal ring of the present invention, omitting an upper wall surface body. 3 and 6 are elevational views schematically showing a touch roll for supporting the ring during molding from the rear side. FIG. 4 is an elevational view schematically showing a link mechanism of a backup roll that supports the ring during molding from the front side. FIG. 6 is a schematic side view of the ring material supply device.

As shown in FIG. 1, the forming roll 10, the mandrel 20, and the mandrel receiving roll 30, which are the basic constituent elements of the present invention, have their axes centered at the same height, and are seen in FIG. As can be seen, their centers are collinear. The constraining frame body 70 in the present invention is composed of four wall surface bodies, that is, an upper wall surface body 71, a lower wall surface body 72, a front wall surface body 73, and a rear wall surface body 74, each having a rigid wall structure.
The forming roll 10 is located on the front wall surface 73 side, and the mandrel 20 and the mandrel receiving roll 30 are sequentially arranged on the rear side. A flywheel 14 is provided at one end of the roll shaft 11 of the forming roll 10 and applies an inertial force to the forming roll 10. The front wall surface body 73 and the rear wall surface body 74 are joined and restrained to the upper wall surface body 71 and the lower wall surface body 72 by a fitting key 75. Forming roll 10, mandrel 20, mandrel receiving roll 3
Two upper linear motion guide rails 47, 47 are arranged symmetrically in the lower part of the upper wall surface body 71 in parallel with the arrangement of 0 and are arranged in the rear wall surface body 74.
From the upper wall body 71 to the position of the mandrel receiving roll 30
It is provided integrally with. On the upper part of the lower wall body 72, two lower linear motion guide rails 48, 48 are symmetrically provided integrally with the lower wall body 72 from the rear wall body 74 to the front wall body 73.

A roll shaft support frame 13 supporting the forming roll shaft 11 of the forming roll 10 is screwed and fixed to the front wall body 73. On the rear part of the forming roll 10, the mandrel shaft support frame 23 is provided on the lower linear motion guide rail 48 and the moving guide device 40 of the mandrel 20 including the mandrel linear motion block 24 placed on the lower linear motion guide rail 48. The mandrel linear motion block 24 is mounted on the mandrel linear motion block 24, and is mounted on the linear motion guide rail 25 of the mandrel feed mechanism 90 in the left-right direction perpendicular to the front-back direction. The movable mandrel shaft support frame 22 that supports the other of the mandrel shafts 21 is provided on the mandrel feed mechanism linear motion block 26 mounted on the linear motion guide rails 25 of the left and right mandrel feed mechanism, and the mandrel is driven by the AC servomotor 92. 20 of the mandrel shaft 21 is attached to the mandrel shaft support frame 22 from the other mandrel shaft support frame 23 side through the mandrel 20, and is pulled out to the mandrel shaft support frame 23 side to pull out from the material ring 2. Remove the mandrel 20.

Mandrel receiving rolls 30 composed of two discs are disposed on the left and right sides of the material ring 2 so as to come into contact with the rear portion of the mandrel 20. The mandrel receiving roll 30
2 provided in the lower part of the upper wall body 71 and extending in parallel to the front and rear
Vertical movement between the upper linear motion guide rails 47, 47 of the book and two lower linear motion guide rails 48, 48 provided in the upper portion of the lower wall surface body 72 and extending in parallel in the front-rear direction, respectively. A linear motion block 49 that fits in a restrained state and can move back and forth, that is, an upper linear motion guide rail 47 and a lower linear motion guide rail 48, and upper and lower linear motion blocks 49, 49.
A roll shaft 31 is horizontally supported by a bearing support frame 32 screwed to the front portion of a linear guide block 46 having a movement guide device 50 for the mandrel receiving roll 30. A feed screw 80 is rotatably screwed from the rear side of the linear guide block 46. On the other hand, the feed screw 80 is rotatably supported by the rear wall surface body 74 and is axially supported while being restrained without moving in the front-rear direction. Therefore, the linear guide block 46 is screw-fed back and forth by the rotation of the feed screw 80. Therefore, the mandrel receiving roll 30, which has the roll shaft 31 supported by the bearing support frame 32 attached to the front portion of the linear guide block 46, moves back and forth in the direction of the mandrel 20 to back up the mandrel 20. The rotation of the feed screw 80 is caused by the pulley 33 provided at the rear end of the feed screw 80.
AC servo motor 91 arranged on the side of this cold forming apparatus
A driving force is applied from the belt by the belt, and the feed screw 80 is rotationally controlled.

On the roll shaft 11 of the forming roll 10, two links 121 and 122 are coaxially and rotatably arranged at positions laterally offset from the forming roll so as not to interfere with the material ring 2. ing. Links 121 and 1 shown in FIG.
Reference numeral 24 shows another embodiment, in which the link is provided with a shaft support 1
It is composed of a rotatable link at 23. At the rear ends of the two links 121 and 122, there are respectively backup roll shafts 133 extending laterally to the front part of the material ring 2, and one backup roll 131 and one backup roll are provided on each of the backup roll shafts 133. The roll 132 is rotatably attached, and the forming roll 1
The upper and lower positions of the outer peripheral surface of the ring 3 during molding on the 0 side are backed up. The two link rolls 12 and 13 are arranged so that the two backup rolls 131 and 132 are located above and below the ring 3 during molding.
1, 122 are crossed and fitted onto the roll shaft 11, and both links 121, 1 on the side opposite to the backup rolls 131, 132
A coupling link 141 is pivotally provided at the front end of 22. A pneumatic or hydraulic pressure cylinder 150 is arranged via these connecting links 141. This pressure cylinder 15
The link 121 and the link 122 are opened and closed by expansion and contraction of 0. That is, when the pressure cylinder 150 contracts and the connecting link 141 is pulled forward from the front wall surface body 73, the link 12
A force acts in the closing direction of the first and the second rolls 122 to reduce the distance between the upper and lower backup rolls 131 and 132.
Therefore, the two backup rolls 131 and 132 are brought into contact with the ring 3 during molding to pressurize and back up, thereby suppressing the vertical movement and vibration of the ring 3 during molding. Ring 3 being formed by backup rolls 131 and 132
The roundness of the product ring 4 can be made more precise by slightly changing the force applied to the product ring 4 according to the material and ring diameter of the ring 3 during molding.

As shown in FIG. 3, the upper wall body 71 is provided with a linear gauge device 110 driven by an air cylinder 111. Linear gauge device 110
Is the linear motion block 11 fitted to the linear motion guide rail 47.
An arm 113 extends downward from 2 to the rear of the ring 3 during molding. Two free-rotating touch rolls 114 and 1 are vertically separated from each other near the tip of the arm 113.
15 are attached. Both touch rolls 114 and 115 are located in two contact points on the rear surface of the ring 3 during molding with a small average pressure and are constantly in contact with each other, and constantly monitor the outer diameter of the ring 3 during molding. The displacement of the positions of both touch rolls 114 and 115 causes the arm 113 to move in the front-rear direction, and the movement of the arm 113 in the front-rear direction is caused by the linear guide rail 4.
The guide block 1 on the upper end side of the arm 113 fitted to 7
The linear gauge device 110 consisting of 12 constantly measures the moving dimension of the guide block 112 with respect to the linear guide rail 47, and the measurement result is used as the AC servomotor 91.
It is interlocked with the position control of the feed mandrel receiving roll 30.

Further, a linear motion guide device 170 is erected on the upper surface of the upper wall body 71. The upper wall surface body 71 is provided with a hole 75 that opens immediately above the processing position of the material ring 2. The linear motion guide device 170 erected on the upper surface of the upper wall body 71 is provided with a linear guide device 96 including a linear motion guide rail 94 and a linear motion block 95 fitted to the linear motion guide rail 94 in the vertical direction. Vertical movement is controlled. An arm 171 having a chucking unit 172 for holding the material ring 2 is provided at the lower end of the linear motion block 95. Linear motion guide device 17
Since 0 moves the linear motion guide device 96 in the front-back direction, the linear motion guide device 99 including the linear motion guide rail 97 extending in the horizontal direction and the linear motion block 98 fitted to the horizontal motion guide rail 97 and moving in the front-back direction is an AC servo motor. The front-back movement is controlled by 100. Then, the vertical arm 17
The movement of No. 1 is controlled by the AC servo motor 93, and the timing is controlled in cooperation with the AC servo motor 92 of the mandrel feeding mechanism 90 to supply the material ring 2 and the mandrel 2.
The retreat timing of 0 is synchronized to prevent the mandrel 20 and the material ring 2 from interfering with each other. The material ring 2 for cold working is supplied to the upper surface of the upper wall body 71, gripped by the chucking unit 172 at the tip of the arm 171 of the linear motion guide device 170, and supplied to the working position where the mandrel 20 is loaded. It

[0023]

As described above, the apparatus for cold forming a metal ring according to the present invention includes a forming roll, a mandrel, a mandrel receiving roll, a mandrel moving guide device, and a mandrel receiving roll moving guide device. , A lower wall body, a front wall body, and a rear wall body, which are attached in a constrained state to a constraining frame body made of a highly rigid wall body, and serve as the moving guide device on the rigid constraining frame body by an LM guide, that is, a linear motion guide. A linear motion guide consisting of a rail and a linear motion block is also incorporated, and its propulsive force is AC.
Servo motors enable each movement to be controlled in cooperation, enabling high-precision cold working not possible with conventional equipment, and forming rolls, mandrels, and mandrels when cold working hard material rings such as bearing steel. According to the present invention, the receiving roll can maintain high accuracy for a long period of time without losing the hardness of the material ring, and the roundness of the outer ring and the inner ring of the ball bearing is conventionally 0.5 to 1.0 mm. In the case of a product having a diameter of 0.1 mm or less, for example, an outer diameter of 120 mm, the deviation of the outer diameter is stable to ± 0.2 mm, which is an excellent effect that the product can be manufactured with high productivity.

[Brief description of drawings]

FIG. 1 is an elevational view showing a metal ring cold forming apparatus of the present invention with a part thereof omitted.

FIG. 2 is a plan view schematically showing the cold forming apparatus for a metal ring of the present invention, omitting an upper wall body.

FIG. 3 is an elevational view schematically showing a touch roll that later supports a ring during molding.

FIG. 4 is an elevational view schematically showing a link mechanism of a backup roll that supports a ring during molding from the front.

FIG. 5 is a side view schematically showing a forming roll, a forming ring, a mandrel, a mandrel receiving roll, and a touch roll.

FIG. 6 is a schematic side view of a ring material supply device.

FIG. 7 is a plan view schematically showing a conventional cold working device for a metal ring.

[Explanation of symbols]

2 Material ring 3 Medium ring 4 Product ring 10 Forming roll 11 Roll shaft 12 Roll shaft 13 Roll shaft support frame 14 Flywheel 20 Mandrel 21 Mandrel shaft 22 Mandrel shaft support frame 23 Movable mandrel shaft support frame 24 Linear motion block 25 Linear motion guide Rail 26 Direct acting block 30 Mandrel receiving roll 31 Roll shaft 32 Bearing support frame 33 Pulley 40 Moving guide device 46 Direct acting guide block 47 Upper direct acting guide rail 48 Lower direct acting guide rail 49 Direct acting block 50 Moving guide device 70 Restraint frame Body 71 Upper wall body 72 Lower wall body 73 Front wall body 74 Rear wall body 75 Hole 80 Feed screw mechanism 81 Male screw 82 Female screw 90 Mandrel feed mechanism 91 AC servo motor 92 AC servo motor 93 AC servo motor 94 Linear motion guide rail 9 Linear motion block 96 Linear motion guide device 97 Linear motion guide rail 97 98 Linear motion block 99 Linear motion guide device 99 100 AC servo motor 110 Linear gauge device 111 Air cylinder 112 Linear motion block 113 Arm 114 Touch roll 115 Touch roll 121 Link 122 Link 123 Shaft support 131 Backup roll 132 Backup roll 133 Backup roll shaft 141 Coupling link 150 Pressure cylinder 170 Linear motion guide device 171 Arm 172 Chucking unit 173 Linear motion block

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-57383 (JP, A) JP-A-10-24338 (JP, A) JP-A-4-59145 (JP, A) JP-A-1- 313122 (JP, A) JP-A-6-142807 (JP, A) JP-A-54-102276 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21H 1/06 B21H 1 / 12 B21K 21/06

Claims (4)

(57) [Claims] 1. A forming roll 10, a mandrel 20, and a mandrel receiving roll 30 are provided, which are arranged horizontally and on the same straight line. (A) Movement of the forming roll 10, the mandrel 20, the mandrel receiving roll 30, and the mandrel 20 Guide device 40 and mandrel receiving roll 30
Each of the movement guide devices 50 is attached to a constraining frame body 70 including an upper wall surface body 71, a lower wall surface body 72, a front wall surface body 73, and a rear wall surface body 74 in a constrained state, and (b) the forming roll 10 is a roll. The shaft 11 is made horizontal, and the upper wall surface body 71 and the lower wall surface body 72 are attached to the front wall surface body 73 which is in a restricted state, (c) The mandrel 20 is attached to the lower wall surface body 72 in a restricted state, (d) Mandrel receiving roll 3
0 is mounted with the roll shaft 31 horizontal to the linear guide block 46 mounted in a restrained state between the upper wall body 71 and the lower wall body 72, and (e) the linear guide block 46.
In the cold forming apparatus for a metal ring, the position of which is controlled from the rear wall surface body 74 by the feed screw mechanism 80 driven by the AC servomotor 91, and which is attached to the rear wall surface body 74 in a restrained state. 2 with 11 as rotation axis
Two links 121, 122 are rotatably attached, and two backup rolls 131, 13 are provided at the rear ends of the two links 121, 122 to back up the ring 3 during molding.
Attach 2 and two backup rolls 131 and 13
The two links 121, 122 are crossed so that the two are located above and below the ring 3 during molding, and the front ends of both links are pneumatically or hydraulically pressure cylinder 1 via a connecting link 141.
A cold-forming apparatus for a metal ring, characterized in that the ring 50 is opened and closed by expansion and contraction of 50 so that the ring 3 can be backed up by the two backup rolls 131 and 132 during molding. 2. The air cylinder 11 is provided on the upper wall body 71.
The 1-drive linear gauge device 110 is attached to the linear guide 47, and the arm 11 is moved downward from the linear gauge device 110.
3 is extended, and two free-rotating touch rolls 114 and 115 are attached vertically apart from each other in the vicinity of the tip of the arm 113, and both touch rolls 114 and 115 are averaged on two rear surfaces of the ring 3 during molding. The cold forming apparatus for a metal ring according to claim 1, wherein the apparatus is positioned in a state of constant contact with a small pressure, the outer diameter of the ring 3 is constantly monitored during molding, and is interlocked with the position control of the mandrel receiving roll 30. . 3. The cold forming apparatus for a metal ring according to claim 1 or 2, further comprising a material ring axial side portion for feeding the mandrel 20 to a material ring 2 forming position from the material ring axial side portion. An apparatus for cold forming a metal ring, comprising a mandrel feeding mechanism 90 driven by an AC servomotor 92 provided. 4. The upper wall body 71 has a linear motion guide device 170 installed upright on the upper surface thereof, and the linear motion guide device 170 descends downward from a hole 75 opening in the upper wall body 71 and has a material ring at the lower end. Supply of the material ring 2 and the mandrel 2 by controlling the timing of the arm 171 having the chucking unit 172 for gripping and the mandrel feeding mechanism 90.
Synchronize the retreat timing of 0 to prevent the mandrel 20 from interfering with the material ring 2 and move the arm 171 up and down.
A C servo motor 93 is provided.
A cold forming device for a metal ring according to any one of claims 1 to 3.